Industry update: Polished concrete flooring developments

by Madelein
Industry update: Polished concrete flooring developments

In our first feature on concrete flooring in 2022, we look at the different levels of sheen and how to achieve them, the types of systems that can be used, installation tips, cost effective solutions and acoustic considerations.

A popular, timeless floor

In recent years, the development in concrete product innovation and the expansion of colours and finishes has seen concrete floors grow in popularity. The resilience of the floors makes them an attractive option for modern homes with a number of industrial markets, such as the food and beverage, hospitality and retail industry turning to polished concrete flooring because of its durability.

Décor updates are also relatively quick and easy as colour changes can be easily achieved by simply changing the aggregate to achieve an all-new look. If, for example, a client wants a grey floor with black stones, simply experiment with the different aggregates to achieve the right look. Options in aggregate sizing range from small 6mm stones to large 19mm stones, each able to provide a unique look.

In addition, the increase in awareness among architects is one of the reasons why this flooring option has become more popular over recent years. Architects have a better understanding of polished concrete floors and that it is a flooring solution for life. In most cases, the floor will last the entire life of the building with very little maintenance. In the retail market, chain stores look for a one-time solution that will last forever. In the residential market, the finishing can be much more decadent.

Know what to expect from a polished concrete floor

In his book, Guide to Polished Concrete Floors, author Bob Harris says that whether you are working with a homeowner or a commercial client, it is imperative that everyone knows what to expect from polishing – both the end product that can be achieved and the process of achieving it.

On residential projects, flooring contractors will typically work directly with homeowners who may have difficulty deciding which flooring system best suits their needs. Often, they will focus on certain characteristics they like, such as a high-gloss finish, a specific colour scheme or ease of maintenance, rather than a specific flooring type. Conversely, when working with architects on buildings and large commercial jobs, they know precisely what their needs are. They have extensively researched the different flooring options and have already chosen polished concrete for a variety of reasons. Bob provides this gloss level table for polished concrete flooring projects:

Depending on the diamond grit that is used, different ranges of polish and different levels of sheen – from matte to a wet and glassy mirror-like finish – can be achieved. Here is an overview of the different levels:

Level 1 polish
Polished concrete is usually categorised in levels ranging from 1 through 4. A level 1 polish can usually be obtained by stopping at the 100-grit resin bond. When you look directly down at the floor, it will appear somewhat hazy with little if any clarity or reflection. This is a good grit for topical sealers.

Level 2 polish
A level 2 polish is obtained by stopping at the 400-grit resin bond, producing a low-sheen finish. When you look directly down at the finished floor and at a distance of roughly 30m, you can start to see a slight overhead reflection, although it is not clear. The grit level produces a low-lustre matte finish.

Level 3 polish
A level 3 polish, achieved by going up to an 800-grit diamond abrasive, will give the surface a much higher sheen than that of a level 2 finish, and you will start to see good light reflectivity. At a distance of 9-15m, the floor will clearly reflect side and overhead lighting. Many big-box commercial stores stop at this finish level because of concerns that a higher degree of polish could produce a slippery surface, especially if the floor becomes wet.

Level 4 polish
This level of polish produces a high degree of shine, so that when standing directly over the surface, you can see your reflection with total clarity. Also, the floor appears to be wet when viewed from different vantage points. A level 4 polish is obtained by going up to a 3000-grit resin-bond diamond or by burnishing the floor with a high-speed burnisher outfitted with specialty buffing pads.

Image courtesy of Diamond Products

System types

Polished concrete is typically a multistep process requiring the use of machines equipped with diamond-segmented abrasives that grind down concrete surfaces to the desired degree of shine and smoothness. Similar to sanding wood, you gradually progress from a coarser-grit to a finer-grit abrasive until you achieve the desired degree of smoothness and sheen. Grit, in this case, refers to the particle size of the diamond. The higher the number, the finer the grit level.

There are a variety of polished concrete flooring systems on the market. The systems are very different from each other and depend on the type of application and the thickness of the floor.

There is also a minimum slab requirement for polished concrete flooring of 25 MPA. If this strength can’t be achieved, then an additional 50mm, 60mm or 80mm concrete must be poured.

Nothing less than a 25 MPA concrete should be used. If the concrete is softer, then liquid hardeners or concrete densifiers need to be used to harden the surface. It is highly recommended that densifiers are used for most if not all floors, as it will help improve the gloss factor and also give the concrete more durability.

Low MPa or substandard floors can seem to shine from a low angle but looking closer the shine will only come from the aggregate. This is why a combination of correct concrete choice, mixing process and the way in which it is cast is vital to contributing along with the method of grinding and polishing to get the required result.

Maintenance advice

In Europe, a specified maintenance programme is included in a flooring system and facilities managers stick to the programme. In South Africa, maintenance happens on an ad hoc basis. The maintenance contract can be quite complex, depending on whether the floor is installed in a high- or low-traffic area and the type of traffic the floor will receive. Maintenance should be done with a burnisher or polishing machine that has diamond-impregnated pads, which can transform the floor back to its original sheen.

Standard monthly maintenance is recommended using a neutral cleaner and cleaning pads. Do not use any acidic or alkaline based cleaners as these will affect the polish. Foot traffic will also influence how often maintenance needs to be done.

If a solvent-based polishable sealer is used, it will need to be recoated every 3-4 years. More expensive sealers such as a lithium sealer that penetrates the surface will ensure a less frequent maintenance schedule. You just need to apply a bit of sealer every four years and buff it up again, making it a very low-maintenance system.

Acoustic considerations

The acoustics of a space with a polished concrete floor is similar to other hard surface types. In very small, confined areas, there may be a slight echo if the floor is concrete and there are also hard wall finishes. By simply adding normal furniture to the space, a lot of the echo can be absorbed.

Sustainability considerations

With polished concrete flooring being one of the hardest, most durable floors on the market, clients can rest assured that their flooring products won’t end up on the landfill.

“If the floor is installed properly, it will last a lifetime. The excellent longevity of the floor makes it a truly sustainable product,” says Brian Clark, Director at Diamond Products.

“Polished concrete isn’t something that will go out of fashion. Even if it does, you can lay another floor on top of it, so there is no waste,” says Mike Albertyn, owner of Firmarox.

“It’s easy to clean, light reflective and it will last for life of the building as there is very little wear on the floor,” says Richard Hugh, Technical Sales Representative at Superfloor.

Thanks and acknowledgement are given to www.avantesolutions.co.za, www.bobharrisguides.com, www.diamondpc.co.za, www.firmarox.co.za, www.floordaily.net, www.mactool.co.za, www.superfloor.co.za, www.Husqvarnacp.co.za and www.theconcreteinstitute.org.za for some of the information contained in this article.

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